sorry, late to this. I lost three to gapeworm last year and had another three showing symptoms that recovered, two of the three that died, died after treatment. I had wormed a month previously. Its not just pheasants, young starlings and crows can carry it too. My favourite hen nearly died and her chest is somewhat compromised now-gets a bit rattly from time to time. I had one pm'd and all I had to hand was ivermectin. It did seem to do the trick although I wormed with flubenvet asap. horrible blinking things, nasty way to die.